by Ted Beyer
Ever since I was a kid, I have been fascinated with space. I would look up at the stars, and I just knew that other people were up there somewhere, looking back at our little point of light, and thinking the same kind of thoughts. On the day I turned seven, Neil and Buzz landed on the moon and I was sure that—somehow—when I grew up, I would get there, too.
Incidentally, that’s me in the red on the right in the picture below. And on the left? Well, that’s Buzz Aldrin!
5 Comments | 
astronomy, Earth Science, Elementary level, High School level, life science, Middle School level | Tagged: apollo 11, astronomy, Buzz Aldrin, Campo del Cielo, chondrule, Ghubra meteorite, meteorites, parent friendly, PBL, restoring meteorites, Seymchan Pallasite, space, Tucson Gem and Mineral Show | 
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Posted by Tami O'Connor
by: Ron Perkins
Who knew that a single coin could be used for so many classroom science activities! You can demonstrate concepts such as surface tension, buoyancy, and even eddy currents with Japanese yen coins!
Surface Tension: Even though aluminum has a density of 2.7 gm/cm3, and the density of water is 1 g/cm3, aluminum yen coins can float on the surface of the water!
Surface tension is a physical property of water. It is caused by cohesion, which is the attraction of like molecules. Water molecules are made up of two hydrogen atoms and one oxygen atom. The “stickiness” of water is caused by hydrogen bonding. This hydrogen bonding pulls the water molecules towards one another and forms a sort of “skin” on the surface of the water.
Using a bent paper clip or a plastic fork, gently lower the flat side of the coin onto the surface of a pan or cup of water and remove the clip or fork. The coin should rest on the surface of the water. Read the rest of this entry »
1 Comment | Chemistry, Elementary level, experiments, Middle School level | Tagged: buoyancy, density, eddy currents, floating, hydrogen bonding, parent friendly, phenomenon based learning, surface tension, variables, yen | Permalink
Posted by Tami O'Connor
by: Ron Perkins
Cartesian Divers are one of the oldest and most interesting toys you can build at home. While they are easy to construct, there is a lot of science behind the workings of this deceivingly simple toy. A Cartesian Diver is an object whose density changes with pressure. In fact, most Cartesian divers become denser as pressure is increased. By constructing a Cartesian Diver carefully, it is possible to make a diver that floats in water at atmospheric pressure, and sinks when the pressure is increased.
Water has a density of about 1 gram/ml. Objects that have a density of less than 1 gram/ml float, while objects with a density greater than 1 gram/ml sink. When using sealed divers, as pressure is increased, a Cartesian Diver’s density might increase from about .8 grams/ml to 1.2 grams/ml. When this happens, the diver sinks in water. Cartesian Divers often change their density by changing the amount of water they displace (i.e., changing their volume). When the pressure is increased, the air inside the diver is compressed. This compressed air takes up less space, and thus displaces less water. As less water is displaced, the density of the diver appears to increase and the diver sinks.
Materials:
1 Plastic Pipet (PP-222), 1 Ballast Nut (CD-3), Plastic Soda Bottle with Top, Candle, Scissors, Pliers, Water
Optional: cap of a Fizz-Keeper Pump (CD-4), Food Coloring, Aluminum Foil, Hot Melt Glue Gun
Instructions
1. With scissors, snip off all but 2 cm of the neck of the pipet.
2. Screw one ballast nut onto the remaining 2 cm neck of the pipet.
3. Fill the pipet bulb with colored water. Note that the bulb must float when placed in a cup of water. Experiment with different amounts of water, making sure that the bulbs still float. Bulbs that float higher in a cup of water will make divers that are more difficult to sink.
4. Your Cartesian diver is ready! Fill a 1 or 2 liter plastic soda bottle almost to the top with water. Place your diver in the bottle and screw on the Fizz-Keeper pump cap. Try squeezing the bottle. Can you make your diver sink? Now pump the Fizz-Keeper and watch as your diver sinks right to the bottom. Can you figure out how to get it back up to the top?
5. Remove the pump cap, pour out your diver, and try varying its buoyancy. Try filling it with different amounts of water. Put it back in the bottle, replace the pump cap and try sinking it again.
6. When you are satisfied with your divers and would like to make it permanent, you can seal it by sealing the open end of the bulb. This can be done with any waterproof glue, hot glue, or by melting the plastic stem slightly and squeezing it gently with small pliers.
To seal the bulb by melting, first make sure your bulb floats. Once it is sealed, its starting buoyancy cannot be changed! Make sure there is no water in the neck by holding it upside down and tapping or squeezing it slightly. Hold the neck about 1-2 inches above a candle flame until it becomes completely transparent (the change is very subtle). Immediately remove the neck from above the flame and squeeze the end gently with pliers to seal. Let cool. Return your diver to the bottle with clean water and it will last for many years.
There are literally hundreds of experiments you can try! For instance, try crumpling up a piece of aluminum foil into a small ball. Place this in your bottle. See if you can sink it by squeezing the bottle… how about pumping it? Small packets of soy sauce have also been known to work!
Use more pipets and vary their densities. Try numbering your divers and see if you can make them sink in order. Note that your divers are not yet sealed, and so they can be adjusted as many times as you like (colored water will leak out of them until they are sealed).
Educational Innovations carries a full line of Cartesian Diver materials, including Bob Becker’s DVD that demonstrates and discusses a plethora of fascinating diver designs. Bob Becker, an award winning high school chemistry teacher, is a pioneer in the field of Cartesian divers. This DVD includes DVD-ROM which contains additional resources such as project guides and templates.
Leave a Comment » | Chemistry, College level, density, Elementary level, experiments, High School level, Middle School level, Physics | Tagged: Bob Becker, Cartesian Diver, parent friendly, phenomenon based learning | Permalink
Posted by Tami O'Connor
by: Norman Barstow
Frequency, Wavelength and Pitch:
Sound is a tone you hear as the result of regular, evenly spaced waves of air molecules. The most noticeable difference is that some tones sound higher or lower than others. These differences are caused by variations in spacing between the waves; the closer the waves are, the higher the tone sounds. The spacing of the waves – the distance from the high point of one wave to high point of the next one – is the wavelength.
8 Comments | Elementary level, experiments, Middle School level, Physics | Tagged: frequency, parent friendly, pitch, sound, tone, vibration, wavelength | Permalink
Posted by Tami O'Connor
by: Tami O’Connor
One of the units I enjoyed most as a middle school teacher was the section on energy. The many awesome hands-on experiments generated such a series of oohs and aahs that it made my already-enjoyable days even more enjoyable! One of my favorites was a lesson that dealt with the Law of Conservation of Energy. A consequence of this law is that energy cannot be created, nor can it be destroyed. (The students would have already explored potential and kinetic energy before the following activity.)
I initiated this lesson reviewing what happens with energy in a closed system. The students clearly remembered comparing the amount of potential energy to kinetic energy using the example that the height of a roller coaster’s first hill is always greater than the height of any of the remaining hills. It is, of course, possible to have a little hill followed by a higher hill as long as the roller coaster is going faster at the top of the little hill than the next higher one. The students were generally able to explain the transfer of energy including heat energy and sound energy in the overall system.
8 Comments | energy, experiments, Middle School level, Physics | Tagged: discrepant event, kinetic energy, Law of Conservation of Energy, parent friendly, phenomenon based learning, potential energy | Permalink
Posted by Tami O'Connor
